gladwell dot com / The Sports Taboo: "Or consider, in a completely different realm, the problem of hypertension. Black Americans have a higher incidence of hypertension than white Americans, even after you control for every conceivable variable, including income, diet, and weight, so it's tempting to conclude that there is something about being of African descent that makes blacks prone to hypertension. But it turns out that although some Caribbean countries have a problem with hypertension, others-Jamaica, St. Kitts, and the Bahamas-don't. It also turns out that people in Liberia and Nigeria-two countries where many New World slaves came from-have similar and perhaps even lower blood-pressure rates than white North Americans, while studies of Zulus, Indians, and whites in Durban, South Africa, showed that urban white males had the highest hypertension rates and urban white females had the lowest. So it's likely that the disease has nothing at all to do with Africanness."